Mine blasts



Jan 5, 1959 A. A. K; A. E. DEMELENNE 2,857,17

MINE BLAsTs Filed March 31, 1954 Jamal/l (l a 7 INVENTOR DML MINE BLASTSAnatole a. k. a. Edgard Demelenne, Mons,Belgium Application March 31,1954, Serial No. 420,195

Claims priority, application Belgium April 10, 1953 2 Claims. (Cl.102-22) This invention relates to 'blasting in mines, and moreparticularly concerns means whereby such blasting may be effected withgreater security and in a simpler manner than heretofore, while at thesame `time providing in addition for improved working conditions in themines Where these blasts are effected.

In the Belgian Patent No. 515,939 dated December l, 1952, and thecorresponding British application No. 33,187/53 dated November 30, 1953,both for: Improvements in means for opposing dust in workings,particularly in coal mines it is proposed to inject a liquid into therock or the coal layers while making use of the detonation of anexplosive to ensure the injection, using the explosive cartridgesusually employed in mine blasts, but however only using those calledsafety cartridges where fire-damp is present or presumed to be present.The injection liquid may be any liquid in pure or mixed form, insolution or other state, particularly water.

It s known that in mine blasting, both in rocks and in coal, both inlevels and cuttings, when the detonation of the explosive is effected inthe presence of a quantity of a suitable liquid the inflammatory effectof the explosion on the fire-damp and the lire-damp mixtures iseliminated or at least considerably reduced.

It has been found that good results may be obtained by using water asthe inammation inhibiting liquid.

However the action of the selected inhibiting liquid may be improved bythe judicious addition of materials or substances having by themselvesan inhibiting effect on the inflammation, as for example sodium chlorideor calcium chloride which are knownto possess this property.

The preferred form under which the addition may be associated to theinhibiting liquid is in solution, but the additional materials orsubstances may be also simply mixed with, or suspended in the liquid.

According to the explosive used, the selected inhibiting liquid, theadditive incorporated therein, and the precise result to be attained,the quantity of the liquid is proportioned.

In blastings, either effected in the usual manner or in the presence ofa liquid as hereabove indicated and in this latter case whether theliquid is used for injection, or for mining operations, subsequently tothe loading of the mine holes the entrance of said holes is closed by atamping. In prior practice, such a tamping has been commonly made ofclay or of solid particles more or less strongly rammed, but such atamping may be formed also with advantage by means of a liquid charge.

The liquid of the charge serving as a tamping may also act, at least inpart, for laying down the dust of the blast.

As liquid, use may be made of any non-inammable liquid and naturally ofany inflammation inhibiting liquid, together with the addition ofmaterials or substances having by themselves an inflammation inhibitingaction, preferably in a soluble or dissolved form.

The quantity of liquid to be used may vary in accordance with thetamping to 'be made and the other conditions of blasting.

assaut Patented Jan. 6, 1959 Moreover, as the tampngliquid may intervenein the desired action-injection for the dust laying, or inhibition ofthe inammation in a mining operation, or the laying of the blast dust,or several of these aims simultaneously the quantity of liquid providedfor the tamping may be modified accordingly.

In firing effected by means of tampings, a reduction in the quantity ofdust formed has been noticed and also that the puff of fume resultingfrom the detonation was less opaque than in the case of the usual claytamping. It is believed that this results from some absorption by theliquid of the detonation products.

Means may be provided for amplifying .the effects referred to, thusimproving the conditions making for safety and health in the mines.

To this end there is yadded to the liquid forming the tamping asubstance adapted to reduce the surface tension of said liquid, `orsubstances or products capable of increasing the agglomeration of thetine dust particles which are thus more easily and more rapidly laiddown and thus become innocuous or less noxious.

Accordingly, the liquid used as tamping comprises materials orsubstances able to attenuate or suppress the toxicity of .the gases andfumes evolved by the explosion, in particular materials or substanceswhich, by reaction with poisonous gases, such for example as CO, NO, NO2or SO2, render the latter innocuous or less noxious.

Naturally these additional materials or substances arel so selected thatfrom mutual reaction, no noxious or otherwise undesirable compounds'will result, especially compounds able to alter the inflammationinhibiting effect of the liquid against fire-damp.

The manner in which the presence of the inhibiting liquid is ensured atthe moment the detonation takes place may vary, but it is convenient toarrange the inhibiting liquid in the form of portable charges.

Where the liquid charge is mainly intended to serve as a tamping,preferably this charge is a portable element.

Preferred embodiments of .the invention will now be described withreference to the annexed drawing, where- 1n:

Figs. l and 2 illustrate in plan View and end View, respectively, anenveloped liquid charge;

Figs. 3 and 4 illustrate in `plan View with parts broken away, and endview, respectively, a modified construction of enveloped liquid charge;

Figs. 5 to 7 illustrate Various arrangements of `blasting cartridges andliquid charges' in mine holes.

Referring to Figs. l and 2, in accordance with one embodiment, theliquid is introduced Within a shell 1 which is sealed or otherwiseclosed and the cross section `of which is made to conform to the minehole, the constitutive material yof the shell being water-proof and notgiving rise to llame firing in order to avoid combustion of portions ofthe shell that could last after the explosion, and, preferably, beingflexible.

When the liquid charge is to perform an inhibiting function, naturallyit kwill be desirable that the shell be easily ruptured by theexplosion, and on the other hand tests have shown that no inconvenienceor detrimental results are experienced should the material of the shellbe ruptured by the explosion where the liquid batch serves as a tamping.

For forming the shell use is made of synthetic plastic material orsynthetic resins answering the indicated requirements and moreover beingsuiciently stiff to enable the shell, even when made with thin walls towithstand the necessary handling without damage.

The sealing of the shell may able means such as associated closuremembers, sticking welding, and particularly autogenous Welding, as shownat in and 1b.

be effected by any'suit" Where the liquid is enclosed within a shell,and particularly a shell made of a pliable or flexible material, asaforesaid, and is used as a tamping there is associated therewith ameans ofindicatingathe integrality of the shell, and convenientlyapmeans adapted for visualv observation, this permitting the user toeasily ascertain the effective presence of a tamping in a mine hole andthe condition of the tamping at the moment the blast is effected. Y y

Particularly, spots or coverings such as those designated by 1c may beformed on theshell by means of a fluorescent or phosphorescent or lightreflecting product or paint. Where the shell is made of transparent ortranslucent material, a phosphorescent or fluorescent substance may beincorporated in the liquid therein.

In both cases, instead of a single shell, the tamping may bev providedwith la first shell 1 containing the liquid, which shell may be made ofa more frangible material, for example a thin synthetic plasticmaterial, and this first shell may be surrounded with a second shell 1d-Figs. 3 and 4-which may act as a protective shell and is then to beadapted for correctly vwithstanding the handling operations while, atsuitable selected locations, the protective sell may be removed touncover the first shell and thereby allow for the indicating means 1cassociated with ythe rst shell 1 to be displayed.

For example, the protective shellf1d maybe made of metal, cardboard, orsynthetic plastic material, and shaped in the form of atube open at theends where it permits the ends of the iirst shell to be observed.

In the following there is indicated by way of examples, in what mannersthe invention may be carried into practice, as well as results of testswhich have been effected.

Example 1.Referring to Figs. 5 to 7 and first to Figs. 5 and 6, whateverthe purpose, for injection and, or for mining one may proceed asfollows: in a mine hole 2 of suitable diameter, for example 40 mm., andappro priate length, there is introduced the cartridge or cartridges ofexplosive designated 3 and the usual firing devices ldesignated 4, andthen a shell enclosed charge 1 of inhibiting liquid as above indicated.The entrance of the hole having preferably been closed by means of asuitable tamping 5, the blasting is effected, causing the shell to beruptured and permitting the liquid to form the inammation inhibitingatmosphere.

The positions of the liquid charge and of the explosive cartridges inthe mine hole could be reversed, as also liquid charges could be placedon either side of an ex plosive charge (Fig. 6), or liquid charges maybe caused to alternate with explosive cartridges.

In this Way injection and inhibiting charges may be formed of differentliquids and made separately, all such modifications being naturallywithin the limits of the invention.

In mining or dislocation, blastings, and even when {ire-damp may bepresent, high explosives may be'used with the well known resultingadvantages of efficiency. Thus having in mind a blasting while using ahigh explosive with water as the inhibiting liquid, the quantity ofliquid may be of from 100 to 200 cubic centimeters (cc.) for anexplosive charge of about 100 grs., but in some cases a smaller quantityof liquid may be used.

Where the disturbance or dislocation of the rock andY an injection ofliquid in the cracks are sought, the quantity of liquid will be normallyhigher and as high as possible, giving in any case the desiredinhibiting effect; for example the quantity of liquid may be from 500 to800 cc. or more for au explosive charge of about 100 grs. The followinginammation inhibiting tests have been made:

' In an experimental chamber-gallery containing air with a content of9.25% CH4, that is an eminently inammableatmosphere, by means of theproper conventional or classical arrangement and without tamping, twocartridges each containing grs. of a most disruptive dynamite, werecaused to explode in the presence of 250-300 cc. water, enclosed withina tube having a diameter of 40 mm. and about 25V cm. length, withoutinammation of fire-damp mixture.

In a second test effected under the same conditions but with fourcartridges each of 100 grs. of dynamite and in the presence of anenclosed charge of about 500 cc. of water, no inflammation of thefire-damp mixture has been experienced.

Example II.-In the boring of a level or gallery in hard schists inclinedat 70 to the horizontal, having a normal cross section of 3.5 m. widthat the base and 3 m. height, and comprising at about the middle of theheight a coal layer having an opening of 0.6 m., upon removal of thelayer on 1.2 rn. in front of the working face, four mine holes are boredin the bed of lesser thickness and lesser hardness of the wall of thelayer and eight mine holes are bored in the bed of the roof.

All these holes were bored with 1.4 m. as length and a diameter of 40mm.

A Four of the mine holes of the roof are then loaded as illustrated inFig. 7 with 4 cartridges of dynamite 3 provided with an instantaneousfuse 4 and against thel explosive there is then pushed a tube 1 made ofsynthetic plastic material having a length of 40 cm. and a diameter of35 mm., sealed at its ends and containing about 370 cubic centimeters ofwater. On firing, the mining of the rock takes place normally, the sameas with the tamping of closely packed clay of 40 cm. length as commonlymade.

1%.-All the remaining holes are then loaded in the same manner as above,but using a sheated explosive called Scurit-GrisouPoussire" inaccordance with the Belgian mining regulation and provided with timefuses. Against the explosive there is then pushed in each hole a tube 1of 40 crn. length and a diameter of 35 mm. filled with water as above.When the blasting is initiatedfthe mining occurs normally.

In each case it has been observed that the puff of fumeresulting fromthe detonation was less opaque than in the case of the usual claytamping, which effect is believed to be due to some absorption of thedetonation products by the liquid.

Fume absorption and dust laying Y Example lII.-In a tamping of whichWateris theV constituent, there is added a wetting agent in smallproportion, for example of the order of 1% or less.

Various commercially available wetting products may be used and employedat the dose of 'about 0.1%, and good results have been obtained with awetting product containing ethylene oxide as a base.

Example IV.-In a tamping of which water is the constituent, there isadded oxides, for example Fe203, in a proportion of about 1%, orcarbonatos, for example CaCO3 or Na2CO3, in a proportion of about 2%,these oxides or carbonates being preferably incorporated in the tampingliquid formed as a saline solution containing alkali chloride, forexample at the dose of 5 to 10%. Preferably sodium chloride should beused, which has the advantage of'avoiding the irritation of the throat.

Example V.To the tamping liquid there is added together a wetting agentand products as in Example IV.

Example Vl.-To the tamping liquid there is added oxidising agents such,for example, as potassium permanga nate -KMnO4-, or hydrogen peroxide-HgOgin a proportion of about 1%.

Example VIL-To the tamping liquid there is added together a wettingagent and oxidising agents; or oxides o1" carbonates, particularly inthe liquid formed as a saline solution, and Voxidising agents; or amixture of wetting` agent, oxides or carbonates, particularly in theliquid formed as a saline solution, and oxidising agents.

It results from the tests eected by the applicant that the products andsubstances above indicated (Examples III-VII) do not at all aiTect theinflammation inhibiting eiect against the tire-damp.

Example VILL-A tube of 10 cm. in length, and a diameter of 40 mm.,containing about 120 cubic centimeters of water to which are addedagents and substances as above referred to, in the indicatedproportions, and placed as a tamping in front of 4 cartridges eachcontaining 100 grs. of dynamite, avoid the inammation in an atmospherecontaining 9.5% of fire-damp.

The placing of a tamping formed of an enclosed liquid charge is Veryeasily effected and it will be appreciated that owing to the inventionthere is not only a saving of the substantial time necessary forpreparing and eii'ecting the usual tamping of clay or other solidmaterials more or less strongly rammed, but the security against thetire-damp and dust, and the healthfulness of the workings are increased.

Moreover in case a charge has not exploded, such a tamping is readilyavailable and may be easily withdrawn and the appropriate stepsundertaken to cause the explosion of the charge, without necessity forattempts being made to explode the charge through sympathy, that is byarranging a further charge in the vicinity, as is done in the case withthe clay tamping system.

I claim:

l. A safety device for use with a blasting cartridge coniprising incombination therewith a liquid-tight translucent material casing, acasing lling comprising a name extinguishing medium having luminoussubstances therein to permit the user to determine the presence of thedevice in a mine hole.

2. The .invention as set forth in claim 1 including a second casing,provided with at least one end opening, surrounding the said rst recitedcasing to act as a protective shell.

References Cited in the le of this patent UNITED STATES PATENTS 60,573Shaffner Dec. 18, 232,640 Hallock Sept. 28, 1880 358,611 Heath et a1.Mar. 1, 1887 748,935 Durham Jan. 5, 1904 1,401,328 Erwin et a1. Dec. 27,1921 1,776,770 Bleeker Sept. 30, 1930 FOREIGN PATENTS 9,763 GreatBritain of 1909 127,232 Great Britain Jan. 20, 1919 763,844 France Feb.19, 1934 515,939 Belgium Dec. 1, 1952

